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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  package org.apache.hadoop.hbase;
19  
20  import java.io.IOException;
21  import java.util.ArrayList;
22  
23  import org.apache.commons.logging.Log;
24  import org.apache.commons.logging.LogFactory;
25  import org.apache.hadoop.util.Shell.ExitCodeException;
26  import org.apache.hadoop.util.Shell.ShellCommandExecutor;
27  
28  /**
29   * A utility for executing an external script that checks the health of
30   * the node. An example script can be found at
31   * <tt>src/main/sh/healthcheck/healthcheck.sh</tt> in the
32   * <tt>hbase-examples</tt> module.
33   */
34  class HealthChecker {
35  
36    private static final Log LOG = LogFactory.getLog(HealthChecker.class);
37    private ShellCommandExecutor shexec = null;
38    private String exceptionStackTrace;
39  
40    /** Pattern used for searching in the output of the node health script */
41    static private final String ERROR_PATTERN = "ERROR";
42  
43    private String healthCheckScript;
44    private long scriptTimeout;
45  
46    enum HealthCheckerExitStatus {
47      SUCCESS,
48      TIMED_OUT,
49      FAILED_WITH_EXIT_CODE,
50      FAILED_WITH_EXCEPTION,
51      FAILED
52    }
53  
54    /**
55     * Initialize.
56     *
57     * @param configuration
58     */
59    public void init(String location, long timeout) {
60      this.healthCheckScript = location;
61      this.scriptTimeout = timeout;
62      ArrayList<String> execScript = new ArrayList<String>();
63      execScript.add(healthCheckScript);
64      this.shexec = new ShellCommandExecutor(execScript.toArray(new String[execScript.size()]), null,
65          null, scriptTimeout);
66      LOG.info("HealthChecker initialized with script at " + this.healthCheckScript +
67        ", timeout=" + timeout);
68    }
69  
70    public HealthReport checkHealth() {
71      HealthCheckerExitStatus status = HealthCheckerExitStatus.SUCCESS;
72      try {
73        // Calling this execute leaves around running executor threads.
74        shexec.execute();
75      } catch (ExitCodeException e) {
76        // ignore the exit code of the script
77        LOG.warn("Caught exception : " + e + ",exit code:" + e.getExitCode());
78        status = HealthCheckerExitStatus.FAILED_WITH_EXIT_CODE;
79      } catch (IOException e) {
80        LOG.warn("Caught exception : " + e);
81        status = HealthCheckerExitStatus.FAILED_WITH_EXCEPTION;
82        exceptionStackTrace = org.apache.hadoop.util.StringUtils.stringifyException(e);
83      } finally {
84        if (shexec.isTimedOut()) {
85          status = HealthCheckerExitStatus.TIMED_OUT;
86        }
87        if (status == HealthCheckerExitStatus.SUCCESS) {
88          if (hasErrors(shexec.getOutput())) {
89            status = HealthCheckerExitStatus.FAILED;
90          }
91        }
92      }
93      return new HealthReport(status, getHealthReport(status));
94    }
95  
96    private boolean hasErrors(String output) {
97      String[] splits = output.split("\n");
98      for (String split : splits) {
99        if (split.startsWith(ERROR_PATTERN)) {
100         return true;
101       }
102     }
103     return false;
104   }
105 
106   private String getHealthReport(HealthCheckerExitStatus status){
107     String healthReport = null;
108     switch (status) {
109     case SUCCESS:
110       healthReport = "Server is healthy.";
111       break;
112     case TIMED_OUT:
113       healthReport = "Health script timed out";
114       break;
115     case FAILED_WITH_EXCEPTION:
116       healthReport = exceptionStackTrace;
117       break;
118     case FAILED_WITH_EXIT_CODE:
119       healthReport = "Health script failed with exit code.";
120       break;
121     case FAILED:
122       healthReport = shexec.getOutput();
123       break;
124     }
125     return healthReport;
126   }
127 }